1. Technical Field
The present invention relates to a data storage device typified by a hard disk drive and, more specifically, to an attachment position of an acceleration sensor which detects vibrations applied to a data storage device.
2. Description of the Related Art
A hard disk drive (hereinafter referred to as an HDD), which is a most general data storage for a computer, has a structure in which a single magnetic disk or a plurality of magnetic disks are arranged coaxially and in which the magnetic disk or disks are driven by a spindle motor. Read and write operations of data are carried out by a magnetic head provided so as to face the magnetic disk, and the magnetic head is driven by an actuator, or a voice coil motor (hereinafter referred to as a VCM) in general. The magnetic disk or disks, the magnetic head, and the actuator are contained in a case which is called an enclosure case. The enclosure case is composed of a base made of aluminum alloy having a thin box shape and a top cover for sealing an opening of the base.
The base has a circuit board fastened on a back surface thereof. The circuit board is mounted with elements for controlling the spindle motor, the VCM, and the like. The circuit board is provided with an interface cable connector for establishing a connection with a computer apparatus which serves as a host. At a position on a far side of the interface cable connector, a preamplifier connector is provided. The reason why the preamplifier connector is located on the far side of the interface cable connector as described above is that a wiring distance between the preamplifier connector and the preamplifier can be shortened. On the other hand, the reason why the interface cable connector is located on the same side of the spindle motor is that the above described arrangement is thought to be best based on electrical constraints such as an intensity of a signal, digital or analog, and a noise, along a flow of the signal viewed from the interface cable connector, and based on geometrical constraints such as a position and a size of the VCM included in the enclosure case.
However, in a case of adopting a configuration in which the circuit board and the interface cable connector are arranged as described above, the circuit board and the spindle motor take up a space in a height direction and a horizontal direction. Accordingly, there has been a problem in which the spindle motor is subjected to the geometrical constraints and in which the optimal design point is difficult to be selected.
In Japanese Patent Publication No. 2620526, proposed are an arrangement of a circuit board and an interface cable connector in a magnetic disk device in which a degree of freedom in locating a spindle motor can be increased while satisfying the above described electrical constraints, and a magnetic disk device having such an arrangement. This proposal is an HDD which includes an enclosure case and a circuit board attached to an outer surface of the enclosure case, the enclosure case containing part of a spindle motor for rotating the HDD and a VCM for controlling a position of a carriage which has a magnetic head for reading magnetic information from a magnetic disk and writing magnetic information to a magnetic disk, the circuit board having an interface cable connector for establishing a connection with a host at one end portion thereof. Here, the circuit board is located at a position on the outer surface of the enclosure case, the position being behind the carriage and the voice coil motor, so as not to conflict with the part of the spindle motor protruding from the outer surface of the enclosure case. Meanwhile, the interface cable connector is located on a far side of the spindle motor.
According to the above described HDD, the circuit board does not conflict with the spindle motor, and the interface cable connector is located on the far side of the spindle motor. Therefore, it is possible to increase the degree of freedom in locating the spindle motor without being subjected to a limitation due to the circuit board. In addition, it is possible to optimize a size of the circuit board.
Incidentally, in a magnetic disk device used in a server system or the like, a plurality of HDDs are generally contained in one frame, and a plurality of HDDs can be simultaneously accessed. In such a state, there are many cases in which the HDDs receive vibrations (disturbances) in a rotation direction. Here, the rotation direction denotes a rotation direction in a plane along the circuit board. For an HDD having a rotary type access mechanism such as a VCM, these vibrations in the rotation direction become disturbances in an off track direction, thus causing deterioration in performance of a read operation and a write operation.
Heretofore, a designing of an HDD has been made such that a feedback control gain has a sufficient restraint power with respect to such disturbances. However, in response to decrease in a track pitch, it is becoming difficult to have a sufficient restraint power due to constraints of mechanical resonance in an access mechanism and the like.
In order to solve the problem, as disclosed in Japanese Unexamined Patent Publication No. 2001-344881 and U.S. Patent Publication No. 5426545, proposed is a method of correcting disturbances by detecting vibrations by use of two acceleration sensors and carrying out feedforward control of a VCM